àm-sǹg暗算

to plot against

to plot against; to scheme; to ensnare; to perform mental arithmetic; to do sums in one's head; machination; plot; scheme; trap

English Wiktionary, “暗算” (CC BY-SA 4.0) — https://en.wiktionary.org/wiki/%E6%9A%97%E7%AE%97 · confidence: Medium (Wiktionary, Hokkien)